In U.S. Pat. No. 3,778,614 there is described a method and apparatus for examining an object by means of X- or .gamma.-radiation. A commercial embodiment thereof has a source of X-rays adapted to transmit a beam of radiation through a planar slice of the object to be examined, detector means to detect the transmitted beam after it has passed through the object and means to sequentially translate and rotate the source and detector means about the object during radiographic examination. If there is a malfunction with this commercial embodiment and/or a measured parameter is determined to be outside the predetermined limits therefor, the associated computer automatically turns off the radiation source and registers this operation on a main control console. However, it is not clear that operation of the radiation source is terminated in the event of a computer malfunction, since the computer must order shut down of the source. In such a case, the object being examined, such as a patient, would unnecessarily be subjected to further radiation. Accordingly, it would be desirable to have an axial tomographic system which is not subject to the aforesaid deficiency.